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921.
The Effectiveness of Capillary Barriers to Hydraulically Isolate Salt Contaminated Soils 总被引:1,自引:0,他引:1
The use of capillary barriers overlayed with topsoil to hydraulically isolate highly saline soils was investigated in a greenhouse study. Capillary barriers of 8 cm or greater thickness effectively prevented salt from migrating upward into the topsoil, thus allowing vegetation to be established. The water which drained from the capillary barrier had electrical conductivities on the order of one third that of the underlying saline soil, and should be acceptable for stream discharge. The capillary barriers reduced the flux of water and salt to the groundwater to about one third of that of the control. The results of the study show that capillary barriers can be used effectively to contain salt contaminated soils. 相似文献
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The aerial application of pesticides increased rapidly following the end of the Second World War, as, along with the development of a wider range of synthetic pesticides, more planes and pilots became available. It also became clear that new and previously inaccessible areas could be sprayed from the air. By the 1980s there were around 100 planes in the United Kingdom (UK) capable of spraying pesticides. However, increasing environmental pressure brought about the introduction of tougher legislation to control pesticide usage. The Food and Environment Protection Act 1985 and the Control of Pesticides Regulations 1986 (as amended) introduced tight controls over the application of pesticides from the air. Aerial application of pesticides has been monitored each year by the UK Ministry of Agriculture, Fisheries and Food (MAFF) since 1978, during which time the area treated has decreased significantly. This has been partly as a result of changes in legislation but also due to technological improvements in conventional crop‐protection methods. The area treated from the air in the UK has never risen above 2.5% of the area treated from the ground and in 1998 had fallen to less than 0.04% of the total area treated with pesticides. It is likely that this figure will continue to fall in the future. By 1998, the only pesticides to be sprayed from the air comprised fungicides, herbicides and insecticides. As a group, herbicides comprised the greatest area of treatment and the only target to show an increase in area treated in recent years has been bracken (Pteridium aquilinum (L) Kuhn). © Crown copyright 2000. Reproduced with the permission of Her Majesty's Stationery Office. 相似文献
924.
Tomas Berglf William C Koskinen Henrik Kylin Thomas B Moorman 《Pest management science》2000,56(10):927-931
Sorption–desorption of the fungicide triadimefon in field‐moist silt loam and sandy loam soils were determined using low‐density supercritical fluid extraction (SFE). The selectivity of SFE enables extraction of triadimefon from the soil water phase only, thus allowing calculation of sorption coefficients (Kd) at field‐moist or unsaturated conditions. Triadimefon sorption was influenced by factors such as soil moisture content and temperature; sorption increased with increased moisture content up to saturation, and decreased with increased temperature. For instance, Kd values for triadimefon on the silt loam and the sandy loam soils at 40 °C and 10% water content were 1.9 and 2.5 ml g−1, respectively, and at 18% water content, 3.3 and 6.4 ml g−1, respectively. Isosteric heats of sorption (ΔHi) were −42 and −7 kJ mol−1 for the silt loam and sandy loam soils, respectively. Sorption–desorption was also determined using an automated accelerated solvent extraction system (ASE), in which triadimefon was extracted from silt loam soil by 0.01 M CaCl2. Using the ASE system, which is basically a fast alternative to the batch equilibration system, gave a similar ΔHi value (−29 kJ mol−1) for the silt loam soil (Kf = 27 µg1 − 1/n ml1/n g−1). In order to predict transport of pesticides through the soil profile more accurately on the basis of these data, information is needed on sorption as a function of soil water content. © 2000 Society of Chemical Industry 相似文献
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928.
IR-spectroscopy: a rapid method to estimate the nitrogen effect and relevant parameters of biocomposts The suitability of infrared spectroscopy to estimate the short-term nitrogen effect and relevant parameters of biocomposts was investigated. Models were developed which are based on the infrared spectra (4000—400 cm—1) of 81 different biocomposts. They enable an estimation of the nitrogen and yield effect in a pot trial, and a close prediction of relevant compost parameters (Ct, Nt, Ct/Nt, pH5h). A major advantage compared with the conventional chemical and biological methods is the simultaneous prediction of the nitrogen and yield effect and relevant parameters from the IR spectrum of an ’unknown’︁ compost. In addition, the infrared spectroscopy is considerably more rapid. 相似文献
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Jrme Van Biervliet DVM Dipl ACVIM Marc Kraus DVM Dipl ACVIM Brett Woodie DVM Dipl ACVS Thomas J. Divers DVM Dipl ACVIM Dipl ACVECC Anna Gelzer Dr. Med. Vet. Dipl ACVIM Dorothy Ainsworth DVM PhD Dipl ACVIM 《Journal of Veterinary Cardiology》2006,8(1):69-73
A 5-year-old Holstein cow, pregnant with a valuable calf, was presented with signs of heart failure (tachycardia, peripheral edema, and distended jugular veins) related to pericardial lymphoma and associated cardiac tamponade. In addition, pleural effusion was present in both hemithoraces. Medical treatment, which consisted of repeated pericardiocenteses, placement of indwelling pleural catheters, administration of intravenous fluid therapy, antibiotics and anti-inflammatory drugs, was ineffective in controlling recurrence of clinical signs despite a temporary improvement. A standing thoracoscopic pericardiotomy was performed in an attempt to reduce clinical signs of heart failure and to prolong life. Clinical signs of heart failure abated and no recurrence was seen. Standing thoracoscopic pericardiotomy along with possible corticosteroids can be recommended as palliative treatment in an effort to extend life for reproductive performance in genetically valuable animals. 相似文献